The example (attached below), when compiled by following gcc

-------------------
$ gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../../../gcc-CVS-20050723/gcc-CVS-20050723/configure
--host=i686-pc-linux-gnu --prefix=/usr/local/opt/gcc-4.1
--exec-prefix=/usr/local/opt/gcc-4.1 --sysconfdir=/etc
--libdir=/usr/local/opt/gcc-4.1/lib --libexecdir=/usr/local/opt/gcc-4.1/libexec
--sharedstatedir=/var --localstatedir=/var --program-suffix=-4.1
--with-x-includes=/usr/X11R6/include --with-x-libraries=/usr/X11R6/lib
--enable-shared --enable-static --with-gnu-as --with-gnu-ld --with-stabs
--enable-threads=posix --enable-version-specific-runtime-libs --disable-coverage
--disable-libgcj --disable-checking --enable-multilib --with-x --enable-cmath
--enable-libstdcxx-debug --enable-fast-character --enable-hash-synchronization
--with-system-zlib --with-libbanshee --with-demangler-in-ld
--with-arch=athlon-xp --enable-libada --enable-languages=c,c++,f95,objc,ada
Thread model: posix
gcc version 4.1.0 20050723 (experimental)
---------------------

with

---------------------
gcc -O1 -ftree-vectorize -c -o envsubst-envsubst.o envsubst-envsubst.c
---------------------

results in this:

---------------------
envsubst.c: In function ‘find_variables’:
envsubst.c:234: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.
---------------------

Tested on both i686-pc-linux-gnu and x86_64-pc-linux-gnu with the same result.

gcc version 4.0.1 20050630 (prerelease) seems to take it without problems.

-- 
           Summary: Segfault with -O1 -ftree-vectorize on 4.1.x
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: drab at kepler dot fjfi dot cvut dot cz
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23048